Communication networks having some level of restoration capability to overcome failures and fiber cuts are well known in the art. One challenge with such networks is estimating the amount of restoration capacity needed which, in turn, requires a selection of restoration paths for all circuits. The choice of restoration paths balances the speed of restoration and the amount of restoration capacity deployed.
A failed circuit restores in the fastest amount of time if it finds sufficient capacity on the pre-stored protect path used by the switches. The protect path is typically the shortest path maximally diverse from the service path. If not, it has to crankback and repeatedly attempt to restore on newly calculated paths until one is successful. On the other hand, restoration capacity needs to be shared between unrelated failures or an excess amount of restoration capacity will be needed. Sharing may require that restoration paths other than the pre-stored protect path be used.
There are often multiple choices available for restoration paths for each circuit. In one known technique, the system allocates all capacity on the shortest maximally diverse path and essentially optimizes restoration performance at the expense of capacity. In another known technique, an integer programming formulation minimizes the amount of restoration capacity needed. This method essentially optimizes the cost of capacity and sacrifices restoration performance.
In addition, for any given service path, there can be numerous restoration paths available in the network. The system needs to select one of these multiple choices, and deal with the dimensionality explosion when there are hundreds of service paths. Thus, planning restoration capacity is challenging. Known methods can come up with widely varying estimates of restoration capacity and also propose capacity in different places in the network. The difficulty in estimating restoration capacity further increases if the network is evolving and new (better) restoration paths become available as more nodes and links are added.
It would, therefore, be desirable to overcome the aforesaid and other disadvantages.